Socket head screw



1966 c. H. ANSINGH SOCKET HEAD SCREW Filed May 4., 1964 FIG. 4

INVENTOR. CARL H ANS/NGH Attornev United States Patent Canada Filed May4, 1964, Ser. No. 364,392 1 Claim. (Cl. 859) This invention relates toimprovements in screws and the principal object of the invention is toprovide a screw which can be driven under high torque without danger oftool slip off or twisting off of the head and which can be readilyremoved by means of a :pair of pliers or wrench where the workman doesnot have an appropriate screw driver.

Another important object is to provide a screw as aforesaid which willbe economical to produce and will be of neat attractive appearance.

While slot head screws are vary widely used where appearance or thedevelopment of high driving torques are not a factor, due to thetendency of the driving blade to slip off the slotted screw head and marthe surrounding surface, such screw are not usually employed with forexample, the enamelled or painted surfaces of appliances or the like. Insuch cases socket type screws are employed and of the presently marketedscrews the square recess socket screws as described in my CanadianPatent Number 588,063 are best adapted to preclude tool slip off,especially where a high torque is required to drive in the screw.

Because socket type screws require special driver tools of differentsize for different size screws, a workman or other person may not havethe proper tool available to remove the screws when desired.

According to the present invention, this problem is overcome by formingthe head of a square recessed socket screw as a hexagonal configurationwhereby the screw may be driven by the appropriate square bit withoutdanger of tool slip off and later may be removed by means of a wrench ora pair of pliers,

It will be understood that the forming of a socket in a screw head willreduce the amount of metal in the head for a given head circumference inthe usual circular screw. For the socket to usefully coact with adriving bit, it must be out of round and so the provision of the socketalso creates a problem of variations in socket wall thickness dependingon its shape relative to the head circumference. This problem is not toodifficult to solve where the screw head is circular since thecircumference may be adjusted to provide at the point of minimum socketwall thickness sufficient metal to withstand the requisite drivingtorque load.

Where the head is made out of circular shape, for example, hexagonalshape, the problem becomes much more complicated since the newnon-circular shape tends to create stress variations in the head notpresent in the circular head and the location of the socket in relationto the non-circular head becomes important in order to preclude headsplitting under app-lied torque without requiring the head to have anundesirable size. It is, therefore, an important feature of the presentinvention to provide a relationship between an out of circular head anda socket formation through which the appropriate driving torque can bedeveloped without requiring an excessive head size. In this connection,according to the invention, this problem is overcome by utilizing asquare socket in a hexagonally headed screw and orienting two of thesides of the square of the socket to be substantially parallel to a pairof opposing sides of the hexagon whereby the diagonals joining thecorners of the socket square are in angular relation to the linesjoining the mid points 3,283,638 Patented Nov. 8, 1966 of the opposingsides of the head, the distance between such mid points being theminimum head dimension. Thus, the arrangement provides for a location ofthe corners of the square at which critical stresses are developed indriving wheneb-y these corners are displaced from the minimum headdimension.

These and other objects and features will become apparent from thefollowing details description taken in conjunction with the accompanyingdrawings in which:

FIGURE 1 is a top plan view of a screw embodying my invention;

FIGURE 2 is a mid vertical section partly broken away, taken along theline 22 of FIGURE 1;

FIGURE 3 is a mid vertical sectional view partly broken away taken online 3--3 of FIGURE 1;

FIGURE 4 is a side elevational view partly broken away of the screw ofFIGURES l to 3.

With reference particularly to FIGURE 1, the screw generally designatedat 1 is provided with a hexagonally shaped ,head 2, providing 6 flatsides 3 at the outer circumference thereof. I

As shown in FIGUR'ES 2 and 3 taken in conjunction with FIGURE 1, thehead 2 is bevelled as at 4 outwardly and downwardly from a top circularconfiguration 5 to the sides 6, the bevelled distance, of course, beinggreater at the corners formed by the adjoining sides 3 than at the midpoints of these sides as shown in FIG- URES 2 and 3, respectively. Asshown in FIGURE 3, the sides 3 of the hexagon are substantiallytangential to the circular configuration 5.

The underside of the head is also prerably similarly bevelled at 6, thebevel extending outwardly and upwardly from a bottom circularconfiguration 7. Thus the sides 3 are generally arcuately bounded at thetop and bottom and are of increasing axial depth from a minimum at thecorners or apices 17 to their mid points.

The head 2 is provided with a central socket 8 of square cross sectionwith the side walls of the socket preferably tapering slightly inwardlyand the socket terminating in a conical bottom 9 as described in myCanadian Patent Number 588,063. The entrance to the socket 8 is alsopreferably bevelled as at 10.

The square cross-sectional socket 8 is preferably oriented inrelationship to the hexagonal head 2, so that two of the sides 11 of thesquare socket are substantially parallel to a pair of opposing sides 3of the hexagon circumference of the head. The other pair of sides 11 ofthe square socket will thus be bisected by a line joining one opposingpairs of apices formed by adjoining sides of the hexagon of the head,that is, by the line 22 in FIGURE 1. This arrangement locates thecorners 12 of the square socket so that a line 13 drawn as a diagonalthrough the corners 12 will be inclined to a line 14 joining the midpoints of a pair of opposing sides 3 of the square socket, the line 14constituting the right bisec-tor of such sides 3. Because of thehexagonal and square relati-onship the line 13 will lie at an angle of15 from the line 14.

The above described relationship places the corners 12 ofthe socket 8 ata point inclined 15 away from the position where there would be aminimum thickness of metal between such corners and the most adjacentpoint of the circumference of the screw head as would be the case, forexample, if the diagonal 13 through the corners 12 lay on the line 14.

The screw, of course, has the usual shank 15 provided with threads 16,the nature and pitch of the threads depending on the intended use of thescrew.

In forming the screw, the head 2 is for-med in a two stage operation inwhich a length of wire rod is delivered a first blow at one end to upsetmetal at such end to form the ultimate head, then a sec-0nd blow isdelivered in which single blow the socket 8 is formed and simultaneouslythe final hexagonal head shape is obtained.

Thus, in forming the head, the head is blanked and finally shaped bycold working at room temperature to elfect a cold working andstrengthening of the head while at the same time affording extremelyeconomical manufacture.

The basic circular configuration 5 corresponds substantially to but maybe slightly smaller than the size of the head required for the socket 8in a circular headed screw. In the hexagon screw illustrated the excessof metal beyond the circular configuration is provided almost entirelyat the corners 17 to build up the hexagonal shape. By virtue of therelationship of the socket 8 and the hexagonal head 2 use is made of themetal build up at the corners 17 to increase the wall thickness of thescrew head at the socket corners 12 by virtue of their displacement fromthe line 14, thus allowing for a somewhat smaller circular configuration5 than would be required in the ordinary round headed screw to providethe requisite socket wall thickness at the socket corners. In use, thescrew can be driven by means of an appropriate square cross-section bitwithout danger of tool slip off and the requisite driving torque may bedeveloped without danger of head splitting. At the same time, the screwcan be either tightened or removed by a wrench or pliers without dangerof head buckling. Further, the additional feature of providing forremoval or tightening by means of a wrench or pliers is achieved Withoutrequiring an excessively large head.

While the preferred embodiment of the invention has been illustrated, itwill be understood that variations in the details of construction may bemade without departing from the spirit of the invention and the scope ofthe appended claim.

What I claim is:

A screw having a hexagonal head provided .with a square socket, saidhead being bevelled at the top and bottom to provide six flat sidesmeeting at six apices around the head, said sides being generallyarcuately bounded at the top and bottom and of increasing axial depthfrom a minimum at the said apices to a maximum at their mid points, onepair of the sides of the square of the socket being substantiallybisected by a line joining one opposing pair of said apices and theother pair of sides of the square of the socket being substantiallyparallel to a pair of sides of the hexagon of the head mid way betweensaid last mentioned pair of opposing apices, each corner of said squaresocket being displaced 15 from the next adjacent right bisector ofopposing pairs of sides of said hexagonal head.

References Cited by the Examiner UNITED STATES PATENTS 641,191 1/1900Champion --9 1,066,253 7/1913 Cornelius 859 2,093,646 9/ 1937 Purtell.2,631,624 3/ 1953 Wright 85-45 2,914,984 12/ 1959' Ansingh 85453,182,342 5/1965 Kolec et a1 10-7 FOREIGN PATENTS 436,03 6 4/1927Germany.

1,476 4/1875 Great Britain. 357,468 9/ 1931 Great Britain. 561,452 5/1944 Great Britain.

CARL W. TOMLIN, Primary Examiner.

EDWARD C. ALLEN, Examiner.

M. PARSONS, JR., Assistant Examiner.

